Hi Tatsuhiro, hi *,

Am 21.07.2010 um 17:43 schrieb Peter Pöml:

> Hi Tatsuhiro,
> 
> Am 20.07.2010 um 16:22 schrieb Tatsuhiro Tsujikawa:
>> BitTorrent info hash in .meta4 is wrong.
>> For example,
>> 
>> Using aria2c, I downloaded OOo_3.2.1_Win_x86_langpack_ja.exe.meta4 from
>> http://download.services.openoffice.org/files/localized/ja/3.2.1/OOo_3.2.1_Win_x86_langpack_ja.exe
>> 
>> 
>> In the .meta4 file, it lists magnet link:
>> 
>> <metaurl
>> mediatype="torrent">magnet:?xt=urn:btih:5d79c7fb140a971115ad9372ab6c1a5db94280a2&amp;xt=
>> ...
>> 
>> Info hash is 40 bytes string after "urn:btih:".
>> In this example, 5d79c7fb140a971115ad9372ab6c1a5db94280a2 is wrong info
>> hash. It seems just a sha1sum of OOo_3.2.1_Win_x86_langpack_ja.exe.
>> The correct info hash is d1b96572966c29414d89afebcb267a24ec03541d, which
>> I got from tracker:
>> http://torrent.projects.ooodev.org:6969/stats.html?info_hash=d1b96572966c29414d89afebcb267a24ec03541d
> 
> It looks as if I misunderstood the meaning of the info hash. I thought it'd 
> be the SHA1 sum of the file. However, it seems to be an SHA1 hash of the info 
> section of the torrent. Thanks for pointing this out!
> 
> I have opened a bug in the MirrorBrain bug tracker here 
> http://mirrorbrain.org/issues/issue56 and I hope I can fix the bug before the 
> next MirrorBrain release. (It should be fixed, or the new feature "magnet 
> links" should stay disabled in the next release, while it's broken.)
> 
> Thanks!
> Peter

I believe I have fixed the issue, and download.services.openoffice.org delivers 
the correct BitTorrent Information Hash now:

 % curl -s 
http://download.services.openoffice.org/files/localized/ja/3.2.1/OOo_3.2.1_Win_x86_langpack_ja.exe.meta4
 | grep magnet
    <metaurl 
mediatype="torrent">magnet:?xt=urn:btih:78ebf160c1924d2ff098535bb0362172f467708c&amp;
 [...]

This is not the same hash as the one that torrent.projects.ooodev.org gives -- 
due to a difference in block size (262144 vs. 131072 bytes). Otherwise, it 
should fit. I tested with the smaller block size and verified that the hash 
would be identical in that case.


The hash can also be retrieved by appending .btih to an URL:

 % curl -s 
http://download.services.openoffice.org/files/localized/ja/3.2.1/OOo_3.2.1_Win_x86_langpack_ja.exe.btih
                
78ebf160c1924d2ff098535bb0362172f467708c OOo_3.2.1_Win_x86_langpack_ja.exe

Thanks again!

Peter
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